366 MESSES. E. FKANKLAJSTD AND B. F. DTJPPA'S 



melt at nearly the same temperature (Leucic acid at 73° C, and diethoxalic acid at 

 74°-5°C.). Waage* states that zincic leucate requires 300 parts of water at 16° for its 

 solution, whilst we find that zincic diethoxalate requires 302 parts at 16°C. Doubtless 

 the study of the products of the transformation of these acids will reveal the difference 

 existing between them : we are at present preparing leucic acid for this purpose. We 

 have also mentioned in the experimental part of this paper that diethoxalic acid pre- 

 pared from methylic diethoxalate yields a silver-salt which differs from that obtained 

 with the acid from ethylic diethoxalate ; and we have even noticed indications of a third 

 synthesized isomer ; but we reserve the further inquiry into the nature of these acids 

 for a future communication. 



On the Proximate Analysis of the Adds of the Lactic Series. 



The investigations recorded in the foregoing pages show that the division of acids of 

 the lactic series which we have termed secondary acids, is derived from oxalic acid by 

 the substitution of two atoms of monad alcohol radicals for one atom of oxygen in 

 that acid. This substitution destroys one of the atoms of oxatyl in oxalic acid, thus 

 reducing the latter from a dibasic to a monobasic acid. This theory of the structure 

 of the secondary acids, so unmistakeably indicated by the mode of their formation, we 

 have also extended to the normal acids, which are thus regarded as derived from oxalic 

 acid, by the replacement of one atom of oxygen in the latter, either by hydrogen alone, 

 as in glycollic acid, or by one atom of hydrogen and one of a monad alcohol radical : 



Hitherto we have advanced only synthetical evidence of this constitution ; but the 

 question presents itself, if the radicals indicated by our hypothesis really exist in these 

 acids, can they not be again disentangled from the complex molecule, either in the con- 

 dition in which they entered it, or, at all events, in the form of well recognized deri- 

 vatives % Such analytical evidence, although possessing far less weight than synthetical, 

 may still be of service as corroborative testimony. We will therefore show how such a 

 proximate analysis of these acids may be accomplished, and for this purpose will first 

 endeavour to demonstrate that if in a chain of carbon atoms any two be united by two 

 bonds of each, the remaining atoms being united to each other by one bond only, the 

 chain is more liable to rupture at the point of double junction than at any other. We 

 have shown how in dimeth oxalic acid a weak link of this kind can be developed f ; for 

 if dimethoxalic ether be treated with phosphorous chloride, it is transformed into 

 ethylic methacrylate, the acid of which contains two atoms of carbon in the condition 

 just indicated. The nature of this transformation and the link in the chain which is 

 thus weakened are shown in the following graphic formulae : — 



* Ann. der Ch. und Pharm. Bd. cxviii. S. 295. t Joum. Chem. Soc. vol. xviiL p. 141. 



